疫疠之证，病家每每忌讳，医家故不明言，然口虽不必明言，心内还须认清，若认之不清，不但用药无效，而且开
口便差。认疫若何？于闻见中但有两三人病情相同者，便要留心。留心若何？病有来踪去迹，怪怪奇奇，传变迟速，不
近情理，较诸正伤寒、风温、温热、湿温、暑 等门，迥乎大异者，即疫也。脉证不必大凉，而服大凉之药，似有害而
终无害者，即疫也。脉证可进温补，而投温补之剂，始似安而渐不安者，即疫也。
治疫之法，总以毒字为提纲，凭他如妖似怪，自能体会无疑。君如不信，试观古今治疫之方，何莫非以解毒为主，
吴又可之专用大黄，非解毒乎？张路玉之酷喜人中黄，而以童便配葱、豉为起手方，非解毒乎？叶天士之银花、金汁必
同用，非解毒乎？至于犀角、黄连、生甘草等味，十方九用，非解毒乎？故嘉言喻氏有要言不繁曰∶“上焦如雾，升而逐
之，佐以解毒；中焦如沤，疏而逐之，佐以解毒；下焦如渎，决而逐之，佐以解毒。”观其旨，上中下则有升疏决之异，
而独于解毒一言，叠叠紧接，不分彼此，岂非反复丁宁，示人以真谛也哉。
忆余少时，尝读《内经》云∶“肺藏魄，肝藏魂。”又云∶“肺主气，肝主血。”夫既清阳之气归之于肺，浊阴之血归
之于肝，又何以清阳之魂不归于肺金，浊阴之魄不归于肝木哉？以是析疑于先子，先于曰∶噫！汝之愚也，然亦不可无
此一问。盖人法天地，禀赋阴阳，先天皇极，干南坤北，离东坎西，是以东离日府，反藏庚位之金鸡，西坎月宫，又赖
甲方之玉兔，金中有木，木中有金，金情恋木，木性恋金，是大地冲和之道也，肝魂肺魄，更何疑哉？
相传孙思邈有降龙伏虎之说，余问于先子，先子曰∶此亦当时之寓言耳。盖今之肝气横逆，胁痛呕恶，目张痉厥，
非狰狞之逆龙乎？而肺气不宣，喘急痰壅，便溺俱无，非猖狂之猛虎乎？当此之际，有慧心明手，一剂而其病如失，是
即思邈之降龙伏虎也。子辈读书，由此说而隅反之，自可日进于高明矣。
窃怪今之人学术未精，每咎于药品之未醇，或嫌胶之不陈，或憎连之非川，用桂无交趾之产，用术难于邑之真，诿
辞卸责，不知上古之世，衣服宫室尚有未全，金、石、草、木之品岂如今之悉备耶？然古人未尝不治人也。且医之有药，
犹绘事之有色也。青、黄、赤、黑，色之常也，而淡红、微翠、嫩绿、娇黄，乃绘家均合之巧。寒、热、温、凉，药之
范也，而大小、绥急、奇偶、轻重，亦由医者配合之微妙耳。嗟乎！可以医而不如绘者乎？
读《素问》五运合化之理，有黄气横于甲巳，白气横于乙庚，黑气横于丙辛，青气横于丁壬，赤气横于戊癸，余潜
心仇对，难以自明，及读《天元册》文，有丹天之气经于牛女， 天之气经于心尾，苍天之气经于危室、柳鬼，素天之
气经于亢氐、昂毕，玄大之气经于张翼、娄胃，因以张介宾所绘《运气图》玩索之，始悉天干与二十八宿所处之向，所
合之位，读时虽少开茆塞，然其合化之根源，一定不移之法，则尚难胸中明辙，确乎无疑，由是问于先子，先子曰∶天
下之事不出乎五行，而《河图》为五行之祖，今尔以合化之所以然，而欲溯流穷源，盍以《河图》思之也。夫《河图》
之数，一与六合，二与七合，三与八合，四与九合，五与十合。试屈指天干之次第，甲数居一，巳数居六，乙数居二，
庚数居七，丙数居三，辛数居八，丁数居四，壬数居九，戊数居五，癸数居十，即《河图》生成之数。土为万物
之母，故以为首而相生合化也。此至简至易之事，而人多未有悟及者也。
疫疠这类疾病，患者家属往往忌讳谈论，医生也故意不明确说出。然而，嘴上虽然不必明说，心里却必须认清病情。如果认识不清楚，不仅用药无效，而且一开口诊断就会出错。如何识别疫病呢？只要在见闻中发现有两三个人的病情相同，就要留心观察。怎样去留心呢？疫病有它的来龙去脉，症状怪异奇特，传变的速度快慢不一，往往不合常理，与正伤寒、风温、温热、湿温、暑病等类别截然不同，这就是疫病。脉象和症状并不表现为大热，但服用大寒凉的药物，看似有害最终却无害的，这是疫病。脉象和症状适合进用温补，但投以温补的药剂，起初似乎安稳后来逐渐不安稳的，这也是疫病。
治疗疫病的方法，总以“毒”字作为提纲，任凭它像妖怪一样怪异，自然能体会无疑。如果你不相信，试着观察古今治疗疫病的方剂，哪一首不是以解毒为主？吴又可专门使用大黄，难道不是解毒吗？张路玉特别喜爱人中黄，并用童便配合葱白、豆豉作为起手方，难道不是解毒吗？叶天士金银花和金汁必定同用，难道不是解毒吗？至于犀角、黄连、生甘草等药材，十个方子九个用到，难道不是解毒吗？所以喻嘉言在《寓意草》中有精辟简练的话说：“上焦如雾，宜升散而驱邪，辅以解毒；中焦如沤，宜疏泄而驱邪，辅以解毒；下焦如渎，宜决通而驱邪，辅以解毒。”看他的主旨，上、中、下三焦虽有升、疏、决的不同，唯独对“解毒”这一句话，层层紧接，不分彼此，这难道不是反复叮咛，向人们展示真谛吗？
回忆我年轻时，曾读《黄帝内经》说：“肺藏魄，肝藏魂。”又说：“肺主气，肝主血。”既然清阳之气归属于肺，浊阴之血归属于肝，那么为什么清阳之魂不归于肺金，浊阴之魄不归于肝木呢？因此我向父亲请教这个疑问，父亲说：“唉！你真愚笨啊，但这问题也不可没有。”大概人效法天地，禀受阴阳之气，先天具备皇极之道，乾在南坤在北，离在东坎在西。因此东方的离卦日府，反而藏着庚位（西方）的金鸡；西方的坎卦月宫，又依赖甲方（东方）的玉兔。金中有木，木中有金，金情恋慕木，木性恋慕金，这是大地冲和的道理，肝魂与肺魄的关系，还有什么可怀疑的呢？
相传孙思邈有降龙伏虎的说法，我问父亲，父亲说：“这也是当时的寓言罢了。”大概现在的肝气横逆，导致胁痛呕吐恶心，眼睛张开痉挛厥逆，这不是狰狞的逆龙吗？而肺气不宣畅，气喘急促痰液壅塞，大小便都无，这不是猖狂的猛虎吗？在这个时候，如果有慧心明手的高医，一剂药下去病就好了，这就是孙思邈所说的降龙伏虎。你们读书，从这个说法出发举一反三，自然可以日益进步到高明境界。
私下责怪现在的人学术不精通，常常归咎于药品不够纯正，或者嫌弃阿胶不陈久，或者憎恨黄连不是四川产的，使用桂枝非要交趾出产的，使用白术难以找到邑县产的真品，推卸责任找借口，不知道上古时代，衣服宫室尚且不全备，金石草木的品类岂能像现在这样齐全呢？然而古人未尝不能治病。况且医生有药物，就像绘画有颜色一样。青、黄、赤、黑是颜色的常规，而淡红、微翠、嫩绿、娇黄，则是画家调和运用的巧妙。寒、热、温、凉是药物的范畴，而药量的大小、缓急、奇偶、轻重，也是由医生配合的微妙之处决定的。唉！怎么能认为医术不如绘画呢？
读《素问》五运合化的道理，有黄气横亘于甲己年，白气横亘于乙庚年，黑气横亘于丙辛年，青气横亘于丁壬年，赤气横亘于戊癸年。我潜心对照研究，难以自我阐明，等到读《天元册》的文章，有丹天之气经过牛宿女宿，素天之气经过心宿尾宿，苍天之气经过危宿室宿柳宿鬼宿，素天之气经过亢宿氐宿昂宿毕宿，玄天之气经过张宿翼宿娄宿胃宿。于是借助张介宾所绘的《运气图》玩味探索，才知晓天干与二十八宿所处的方位和相合的位置。读的时候虽然稍微开阔了蒙蔽，但对于合化产生的根源，一定不移的法度，心中仍然难以明晰确凿无疑，于是再次询问父亲，父亲说：“天下的事情不出乎五行，《河图》是五行的祖源。现在你想要探究合化的所以然，追溯源头，何不思考《河图》呢？”《河图》的数理，一与六合，二与七合，三与八合，四与九合，五与十合。试着屈指计算天干的次序，甲数居一，己数居六，乙数居二，庚数居七，丙数居三，辛数居八，丁数居四，壬数居九，戊数居五，癸数居十，这正是《河图》生成之数。土为万物之母，所以放在首位而相生合化。这是极其简单容易的事情，但大多数人还没有领悟到。
The syndrome of epidemic pestilence is often tabooed by the patients' families, and physicians deliberately do not state it explicitly. However, although one need not speak it aloud, one must clearly recognize it in mind. If recognized unclearly, not only will the medication be ineffective, but any diagnostic statement made will be erroneous. How to identify an epidemic? One should pay attention whenever two or three cases with identical symptoms are observed. How to pay attention? Epidemics have their origins and manifestations; their symptoms are strange and bizarre, their transmission speed varies, and they often defy common sense. They are vastly different from regular Cold Damage (Zheng Shanghan), Wind-Warmth (Feng Wen), Warmth (Wen Re), Damp-Warmth (Shi Wen), and Summerheat (Shu) syndromes; such distinctiveness indicates an epidemic. When the pulse and symptoms do not indicate extreme heat, yet administration of extreme cooling herbs seems harmful initially but ultimately harmless, this is an epidemic. When the pulse and symptoms suggest the suitability for warming and tonifying, yet the administration of warming and tonifying formulas initially appears to bring relief but gradually leads to worsening condition, this is also an epidemic.
The method for treating epidemics takes the character "Toxin" (Du) as the guiding principle. Regardless of how bizarre or monstrous the presentation, one can comprehend it without doubt. If you do not believe, observe ancient and modern formulas for treating epidemics; are they not all primarily focused on resolving toxins? Wu Keyi's exclusive use of Rheum Palmatum Root and Rhizome (Dahuang, 大黄) – is this not resolving toxins? Zhang Luyu's strong preference for Human Excrement Yellow (Ren Zhong Huang, 人中黄), combined with infant urine and prepared with Scallion Stalk (Cong Bai, 葱白) and Fermented Soybean (Chi Dou, 豆豉) as a starting formula – is this not resolving toxins? Ye Tianshi's mandatory co-use of Lonicerae Flos (Jinyinhua, 金银花) and Gold Juice (Jin Zhi, 金汁) – is this not resolving toxins? As for Rhinoceros Horn (Xijiao, 犀角), Coptidis Rhizoma (Huanglian, 黄连), and Raw Licorice Root (Sheng Gancao, 生甘草), used in nine out of ten formulas – is this not resolving toxins? Therefore, Yu Jia Yan (Yu Chang) stated succinctly in his work: "The Upper Jiao is like mist; elevate and disperse it, assisted by toxin resolution; the Middle Jiao is like a fermenting vat; dredge and drain it, assisted by toxin resolution; the Lower Jiao is like a ditch; clear and drain it, assisted by toxin resolution." Observing his intent, while the Upper, Middle, and Lower Jiao differ in elevation, dredging, and clearing, the phrase "assisted by toxin resolution" is repeatedly emphasized without distinction. Is this not repeated admonition to reveal the true essence?
Recalling my youth, I read in the *Neijing* (Inner Canon): "The Lung stores the Corporeal Soul (Po), the Liver stores the Ethereal Soul (Hun)." It also states: "The Lung governs Qi, the Liver governs Blood." Since Clear Yang Qi belongs to the Lung, and Turbid Yin Blood belongs to the Liver, why does the Clear Yang Hun not belong to Lung Metal, and the Turbid Yin Po not belong to Liver Wood? I raised this doubt with my father. He said, "Alas! You are foolish, yet this question is not unworthy." Generally, humans emulate Heaven and Earth, inheriting Yin and Yang. In the primordial state, Qian is South and Kun is North; Li is East and Kan is West. Thus, in the East, the Li trigram (Sun Palace) hides the Golden Rooster of Geng (West); in the West, the Kan trigram (Moon Palace) relies on the Jade Rabbit of Jia (East). Metal contains Wood, and Wood contains Metal; Metal loves Wood, and Wood loves Metal. This is the harmonious way of the earth. What then is there to doubt about the Hun of the Liver and the Po of the Lung?
It is said that Sun Simiao proposed the concept of "Subduing the Dragon and Taming the Tiger." I asked my father about it. He replied, "This is merely an allegory of that time." Essentially, current Liver Qi rebellion causing hypochondriac pain, vomiting, wide-open eyes, spasms, and syncope is like a ferocious rebellious dragon. Meanwhile, Lung Qi failing to diffuse, causing rapid panting, phlegm obstruction, and absence of urination and defecation, is like a rampant fierce tiger. At such times, a physician with wisdom and skill who cures the disease with a single prescription is practicing Sun Simiao's subduing of the dragon and taming of the tiger. You scholars should reflect upon this saying and apply it analogously; thus, you will daily advance toward higher understanding.
I privately criticize contemporary practitioners whose knowledge is imprecise. They often blame the purity of medicinal materials, complaining that Colla Corii Asini (Ejiao, 阿胶) is not aged enough, or despising Coptis chinensis (Huanglian, 黄连) if not from Sichuan, demanding Cassia Twig (Guizhi, 桂枝) only from Jiaozhi, and finding difficulty obtaining authentic Atractylodes Macrocephala Rhizome (Baizhu, 白术) from Yixian. They make excuses to shirk responsibility, forgetting that in ancient times, clothing and dwellings were not fully developed, let alone the variety of minerals, stones, grasses, and trees available today. Yet, ancients did treat people successfully. Medicine having herbs is like painting having colors. Blue, yellow, red, and black are standard colors, but pale red, light green, tender green, and delicate yellow represent the subtle artistry of painters. Cold, heat, warm, and cool are the categories of herbs, while dosage size, slowness/rapidity, odd/even combinations, and heavy/light weights depend on the physician's subtle coordination. Alas! How can medicine be considered inferior to painting?
Studying the principles of Five Movements and Six Qi transformation in the *Suwen*, one finds Yellow Qi traversing Jia-Ji years, White Qi traversing Yi-Geng years, Black Qi traversing Bing-Xin years, Green Qi traversing Ding-Ren years, and Red Qi traversing Wu-Gui years. I studied these carefully but found them difficult to clarify independently. Upon reading the *Tianyuan Ce*, which mentions Dan Tian Qi passing through Niu and Nu mansions, Su Tian Qi passing through Xin and Wei mansions, Cang Tian Qi passing through Wei, Shi, Liu, and Gui mansions, Su Tian Qi passing through Kang, Di, Ang, and Bi mansions, and Xuan Tian Qi passing through Zhang, Yi, Lou, and Wei mansions, I consulted the *Yunqi Tu* (Chart of Movements and Qi) drawn by Zhang Jiebin. Only then did I understand the positions and combinations of Heavenly Stems and the Twenty-Eight Mansions. Although this slightly cleared my confusion, the fundamental roots of transformation and the immutable laws remained unclear in my mind. I asked my father again. He said, "All matters under heaven fall within the Five Elements, and the Hetu (River Chart) is the ancestor of the Five Elements. If you wish to trace the source of transformations, consider the Hetu." The numbers of the Hetu are: One combines with Six, Two with Seven, Three with Eight, Four with Nine, and Five with Ten. Counting the sequence of Heavenly Stems: Jia is One, Ji is Six, Yi is Two, Geng is Seven, Bing is Three, Xin is Eight, Ding is Four, Ren is Nine, Wu is Five, Gui is Ten. These correspond exactly to the generating numbers of the Hetu. Earth is the mother of all things, hence it is placed first to generate and transform. This is extremely simple and easy, yet most people have not realized it.